Apparatus for vaporizing liquid fuel



March 11, 1941. W H p-{OAGLAND` I 2,234,407

APPARATUS FOR VAPORIZING LQUIDIFUEL Filed July 25, 1939 To urnmion y fFrVnpor Vapor/ Liquid Level Confrd Patented Mar. ll, 1941 PATENT oFFicEAPPARATUS FORl VAPORIZING LIQUID FUEL Walter H. Hoagland, WebsterGroves, Mo., as-

signor to Shell Development Company, San Francisco, Calif., acorporation of Delaware Application July 25, 1939, Serial No. 286,393

s Clarins.

The present invention relates to the vaporization of liquid fuel and maybe employed in connection with various fuel-consuming devices, such asinternal combustion engines, heaters,

stoves, furnaces and the like.

It has been found desirable to liquefy certain normally gaseouspetroleum hydrocarbons, as for example propane and butane, so that thesame may be distributed to the trade in an economical l0 manner. It thenbecomes necessary to provide a unit capable of revaporizing these1iqueled gases in order to efliciently burn the same. This is due to thefact that liquid propane, for example, contains 690,000 B. t. u.s percubic foot and the same liquid cubic foot will yield approximately 275cubic feet of gas at the same temperature (0 F.) Obviously, the problemof eilicient combustion will be much simpler if the hydrocarbon isutilized in the gaseous state.

an improved unit for carrying out the vaporization of liquefied fuelgases prior to utilization.

It is a further object of this invention so provide an arrangementwhereby advantage is taken of changes in prevailing atmospherictemperatures to decrease the operating expenses of the unit.

Generally speaking, vaporizing units of this type comprise basicallythree elements; a storage place for the liquefied gas, means forreducing the pressure on the liquefied gas, means for vaporizing theliquefied gas by heat exchange and some method of regulating thepressure of the vaporized liquid issuing from the heat exchanger.

Another object of this invention is to provide an arrangement wherebyonly a portion of the demand for hydrocarbon vapors is supplied Athrough'the heat-exchanger, a large portion being supplied directly fromthe top of the storage o tank, automatic controls being provided wherebythe supply of vapors ready for combustion will never be exceeded by anysudden and unusual demand upon the unit. l

Referring to the accompanying drawing. the gure represents a schematicplan of the invention.

In the drawing, a pressure storage tank I is provided with a-liquid lineA, incorporating two shut-off valves 2 and 3, and leading to aconventional -type vaporizer 4 of the heat-exchanger type. A vapor lineB leads from the top of the vaporizer 4 to a gas pressureregulator 5 andthence through vapor line C toa point of utilization. In vapor line B isa pressure relief An object of the present invention is to provide valve6 and shut-off valve 1. Between valves 6 and 'I is a third valve levelcontrol 9.

The vaporizer 4 is provided with a steam line D including a limitpressure control device as designated by I0 and II. j 5 A vapor line Eleads from the top of the storage tank I through a diaphragm valve I2and a shut-off valave I3 to vapor line B.

A vapor line F provided with shut-off valves I4 and I5 and pressurerelief valve I6 leads from 10 the top of tank car 22 to vapor line B. Aliquid line G leads from the bottom of tank car 22 to the bottom ofstorage tank I, this line embodying a shut-o valve I'I, pressure reliefvalve 23, liquid pump I8, shut-01T valve I9, and shut-ofi valve 15 2|.

s operated by a uquid The operation of the system is as follows: Forpurposes of illustration it will be assumed that propane is the fuelbeing used. In this case it has been determined that the followingconditions 20 were, in a particular installation, preferable forsatisfactory operation; the limit control valve I0, II is set to open ata pressure of' 30 pounds per square inch to admit steam to the vaporizer4 and close at 40 pounds per square inch, the dia- 25 phragm valve I2 isset to close at pressures below 25 pounds per square inch, openingagain. at 35 pounds per square inch, and valves I4 and 2| are closed toeliminate tank car 22 and connecting lines from the system. The gaspres- 30 sure regulator 5 is set to deliver propane vapors to vapor lineC at 10 pounds per square inch or at any other desired utilizationpresure. Valves 2, 3, I and I3 are open.

Assuming that the vaporizer is not in operation, 35

` i. e. there is a xvapor pressure in the storage tank in excess of 40pounds per square inch, this pressure, being transmitted to the'limitcontrol valve I0, II and preventing admittance of steam to thevaporizer, and that further the vaporizer 40 is lled to a predeterminedlevel with liquid propane whereby the liquid level control 9 willoperate to close valve 8, then, vapor is supplied to the gas pressureregulator solely from the top of the storage tank through vapor lines Eand 45.l

As the storage tank I which is situated at a higher level than thevaporizer 4 and preferably of a dark color for heat absorption purposescools, .due to changes in outslde'fatmospheric 50 temperature and latentheat of vaporization losses, there will be a corresponding pressure dropthroughout the system on the upstream (high pressure) side of the gaspressure regulator 5.

As soon as the pressure falls to 30 pounds per 55 square inch in thesystem on the upstream side of the gas pressure regulator, the limitcontrol valve IU, Il will open, admitting steam to the vaporizer. Theadmittance of steam, and subsequent vaporlzation of liquid propane inthe vaporizer 4 will force the liquid level down and cause the liquidlevel control 9 to open valve 8 in vapor line B. When this occurs,artificially vaporized propane from the heat exchanger 4 will passthrough vapor line B and join the vapors coming from the storage tank Ithrough vapor line E If at this time, a large amount of vapor is beingused, the pressure on the upstream side of the gas pressure regulatorwill continue to drop; when a pressure of pounds 'persquare inch isreached, the diaphragm valve I2 will close. At this stage, propane willpass only through liquid line A, vaporizer 4 and vapor line B to gaspressure regulator 5. The closing of diaphragm valve I2 will preventfurther utilization of material vaporizing from the surface oi.' theliquid in the storage tank I and thus cause the pressure therein toslowly rise as heat is absorbed from the outside atmosphere. As soon asa pressure of pounds per square inch is reached anywhere in the system,diaphragm valve I2 will reopen and permit vapors from the top of thestorage tank to join those coming from the vaporizer I. When thepressure increases to pounds per square inch, the limit control valveI0, II will shut the steam supply to the vaporizer 4 off, whereupon theliquid level of propane will rise to its predetermined maximum heightand operate the liquid level control device 9 to close valve 8. At thisstage, the starting point of the above description is again reached, i.e., propane vapor is being supplied from the top of the storage tank Ionly. 'Ihe 5 pound pressure ,differential between diaphragm valve I2'and limit control valve I0, I I is maintained to ensure a positivesupply of vapors in the system under any operating conditions.

With the present arrangement it is also possible to rell the storagetank without interfering with the operation of the unit. This isaccomplished in the following manner: Valves I4, I5, I1, I9 and 2| areopened and pump I 8 put into operation. Liquid propane will thus bepumped from the tank car 22 through line G to the storage tank I, whilepressure in the system is equalzed by vapor line F connecting with vaporline B and indirectly with vapor line E.

It is to be understood that the above description is for illustrativepurposes only, cer-tain obvious modifications being included within thescope of the invention, as for example a group of vaporizers may besupplied from a series of storage tanks and vaporized fuels fed to apressure manifolding system rather than as in the simplified unitdescribed. Obviously this valve could also be used to control otherheating media than steam for thevaporizers, as for example gas flames,heated liquids or an electric current. Any

of the commonly utilized, normally gaseous fuels or mixtures of the samethat may be satisfactorily stored in a liquid state under pressure maybe substituted for propane. Other obvious and useful modifications willundoubtedly be apparent to those skilled in the art.

The advantages of present invention over existing units of this type arenumerous, as for example the use of liquid regulators is entirelyeliminated. Such regulators have in the past caused considerable troubleand annoyance due to their tendency to freeze when handling 10W boilingpoint materials. A further particular improvement is the economy ofoperation of the unit, the necessary heat input to the system beinggreatly reduced from that required in conventional vaporising systems.The present unit is inherently flexible enough in operation to meet anysudden and unusual demands placed upon it. Simplicity of constructionand the safety features embodied are also factors that may be consideredas distinct advantages.

I claim as my invention:

1. In apparatus for vaporizing liquefied gas of the class described, avaporizer for liquefied gas, a storage tank for liquefied gas, an inletliquid line for conducting liquefied gas, from said storage tank to saidvaporizer, gas pressure regulating means, an outlet vapor line forconducting vapors from said vaporizer to said gas pressure regulatin'gmeans, a valve interposed in said last-named line, a liquid levelcontrol whereby the liquid level may be maintained within predeterminedlimits in said vaporizer, said liquid level control and said last-namedvalve being arranged and adapted to operate conjunctively, a-vapor lineleading from the top of said storage tank to said previously mentionedvapor line, means for supplying heat to said vaporizer and pressureresponsive means for controlling the flow of heat to said vaporizerincorporated in said apparatus on the upstream side of said gas pressureregulating means.

2. In apparatus for vaporizing liquefied gas of the class described andincluding a storage tank and vaporizer for liquefied gas, an inletliquid line for conducting liquefied gas from said storage tank to saidvaporizer, a rst vapor line leading from said vaporizer, a second vaporline leading from the top of said storage tank to said rst vapor line, adiaphragm valve in said second vapor line operable over a predeterminedpressure range, means for supplying heat to said vaporizer, a limitcontrol valve operable over a predetermined pressure range incorporatedin said apparatus, said limit control valve being arranged and adaptedto control the heat input to said vaporizer.

3. Apparatus according to claim 2 wherein a pressure differentialoperating range between the diaphragm valve and the limit control valveis maintained.

4. In apparatus for vaporizing liquefied gas of the character described,a vaporizer for liquefied gas, a storage tank for liquefied gas, saidstorage tank being so positioned that gravity flow of liquefied gas tosaid vaporizer will take place.

means for supplying heat to said vaporizer, gas

pressure regulating means, a liquid inlet line from said storage tank tosaid vaporizer, a vapor outlet line from said vaporizer to said gaspressure regulating means, liquid level controlling means including avalve in said l-ast-named line whereby the liquid level may bemaintained within predetermined limits in said vaporizer, a' vapor lineleading from the top of-v said storage tank to said first-named vaporline, a diaphragm valve operable over a predetermined pressure rangelocated in said last-named vapor line and a limit control valve locatedin the top of said vaporizer, operable over a predetermined pressurerange and arranged and adapted to control the heat input to saidvaporizer.y

5. Apparatus according to claim 4 wherein the upper limit of operationof the diaphragm valve is lower than the upper limit of the operatingpressure range of the limit control valve and higher than the lowerlimit of the operating pressure range of said limit control valve.

veying vapors from said source of liqueiied gas supply to said rst line,means automatically responsive over a given pressure range of saidapparatus for controlling the heat input to said vaporizer, means formaintaining a liquid level within predetermined limits in said vaporizerand a pressure responsive diaphragm valve. in said 5 second lineoperable over a gven'pressure range.

WALTERH. HOAGLAND.

